Conventionally, cardiac resynchronization therapy (CRT) is known as one of methods for treating heart failure. The CRT is a treatment method for correcting asynchrony in heart motion and restoring a pump function of the heart to nearly a normal state by placing an electrode (a pacing lead) of a pacemaker into an area at which delay in propagation of electric stimulation occurs in the heart (hereinafter, referred to as a delay area). In the CRT, a doctor places the electrode into a vein closest to the delay area while referring to an X-ray image fluoroscopically captured by an X-ray diagnostic apparatus.
Conventionally, delay areas are diagnosed using information of electrophysiology (EP), or by EP mapping in recent years, for example. In recent years, it has been known that delay areas can be diagnosed by a non-invasive analysis using an ultrasonic diagnostic apparatus. Specifically, a method for analyzing heart wall motion quantitatively by echocardiography has been in practical use in recent years. Such an analysis method can display an analysis image in which indices of local heart wall motion (e.g., strain) are mapped on an endomyocardium and between an endomyocardium and an epimyocardium in an ultrasound image in a color tone varying depending on the value. Because a heart is a tissue in which a myocardium is moved by mechanical excitation caused by electric stimulation, a delay area can be displayed as an area in which the heart wall motion is not synchronized (an asynchronous area) in the analysis image. The CRT treatment, however, is carried out under X-ray fluoroscopic guidance, and the analysis image is simply notified to the doctor as prior information to develop a treatment plan. Actually, it is not yet realized that the doctor is informed of a position into which the pacing lead is to be placed under the X-ray fluoroscopic guidance for the CRT treatment. On the other hand, there have been technologies for displaying an X-ray fluoroscopic image with another image superimposed thereon being developed. Since an endocardial surface and an epicardial surface of a heart wall are hard to distinguish, it is difficult to align an X-ray image with an analysis image, that is, an X-ray image with an ultrasound image.